Charles h



c. H. RIPPL.

ELECTROMAGNETIC OVERLOAD DEVICE.

APPLICATION FILED JULY 6.1917- 1,305,937. Patented June 3, 1919.

I N VENTOR.

A TT ORNE Y.

our TED STATES PATENT OFFICE.

CHARLES H. RIPPL, F CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC CONTROLLER & MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

ELECTROMAGNETIC OVERLOAD DEVICE.

Specification of Letters Patent.

Patented June 3, 1919.

Application flled July 6, 1917. Serial No.178,928.

To all whom it may concern:

Be it known that I, CHARLES H. RIPPL,

a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Electromagnetlc Oyerload Devices, of which the following is a specification.

This invention relates to electromagnetlc overload devices.

The principal object of this invention 13 to provide an electromagnetic overload device which, upon the occurrence of overload current conditions in its winding, will oper- 15 ate according to the following characteristics: If the current overload is between predetermined minimum and maximum limits, the device will operate at the end of a time interval after the occurrence of the current overload, the time interval being inversely proportional to the degree of the overload; upon the occurrence of an overload above the said maximum, the time interval will abruptly disappear and the contacts will operate substantially instantaneously; the minimum overload value, the length of the time interval, and the maximum overload value may each be adjusted independently of the others, and the maximum value and the time interval may also be adjusted without materially affecting eachother or the minimum overload value; during the time interval between the'occurrence of an overload andthe operation of the device, if the overload subsides, the device will not operate, but automatically return to the condition prior to the occurrence of the overload.

Other objects will be apparent.

In the accompanying drawing, I have shown a front view, partly in section and broken away, of an overload device embody: ing my invention and adapted to open 'swltch contacts when it operates.

Referring to the drawing, I have shown at 10 the energizin' winding. The magnetic circuit energized y the winding 10 has a main frame 11, a stationary pole piece 12, a stationary thimble member 13, and a movable plunger 14. The pole piece 12 1s adjustabl threaded into the mam frame at 15, an is adapted to be-locked in anyadjusted position by a lock-nut 16. The polar end of the ole piece 12 has a cone-shaped 56 recess 17. he closed end of the magnetlc and tapering 01f downwardly 'tion in the mainframe 11 by a non-magthimble member is exteriorly conical in shape as shown at 18, to correspond to the recess 17 in the pole piece, and is interiorly shaped to a horizontally transverse place as shown at 19, to correspond to the upper end of the plunger 14. Two air gaps are thus formed, a gap 20 between the recess 17in the pole piece 12 and the conical end 18 of the thimble member 13, and a gap 21 between'the under side of the thimble head andthe upper end .of the plunger 14. The side wall 22'of the magnetic thimble opposite the recess therein for the plunger 14 is of graded cross section, being thickest at the upper end where it joins the conical head 18, to a point adjacent to the upper end of the plunger 14 when in the normal position shown in the drawing. The,thimble is held in posineti'c nut 23, screwed into the main frame at'24, a flange 25 on the thimble being clamped between the nut and a shoulder 26 on the main frame. An internal shoulder A 27 on the nut 23 serves as a stop to limit the downward movement of the plunger 14. The plunger 14 carries a non-magnetic stem 28 riveted thereto at 46 and passing up-' wardly throu h the closed end of the thimble member 1 and through the pole piece 12, terminatin at 29 adjacent to a switch memher to be described. The plunger 14 has a tail-piece 30 integral therewith, extending downwardly from the plunger through an opening 31 in the nut 23, and carrying the non-magnetic piston 32 of a dashpot, the piston stem 33 being tubulartand pinned to the tail-piece 30 at 34, and having lateral orifices 35. In the center of the. piston is a ball valve 36. The cylinder ofthe dashpot is shown at 37, and is filled with oil or other fluid medium up to the level marked Oil level, the oil itself not beingindicated on the drawing for the sake of clearne'ss. The upper end of the cylinder of the dashpot terminates in a flange38, by which the dashpot cylinder hangs on an internal shoulder 39 of an exteriorly threaded ring-nut 40, the ring nut in turn being supported by an interiorly threaded supporting ,nut 41, threaded to the ring-nut 40 and to the nut 23. A dashpot nut 42 is adjustably thremed on the lower end of the dashpot cylinder 37, and is .locked in any adjusted osition by "the lock-nut 43. Between the ashpot nut 119 42 and the ring-nut 40 is a compression spring 44. The dashpot cylinder is capable of movement vertically, the flange 38 sliding axially in the ring-nut- 40, but the action of the spring 44 normally holds it in its lowermost position, with the flange 38 on the shoulder 39 of the ring-nut 40. The relatlWE axial position of the piston 32 and the cylinder 37 is adjustable by raising or lowering the dashpot cylinder, this being accomplished by adjusting the position of the ring-nut 40 in the supporting nut 41, the adjustment being fixed by a lock-nut 45. The internal diameter of the cylinder 37 at the lower'end thereof is only slightly larger than the outside diameter of the piston, but the diameter of the upper end of the cylinder is considerably larger than the diameter of the piston, this greater diameter beginning abruptly at 45 for a purpose to be described.

The parts thus far described are mounted on a slate, or other supporting means 50. Mounted on the same support is a movable switch-arm 51, pivoted to the support at 52, and having a contact member 53. Mounted onthe support 50 is a stationary contact 54, and when the switcharm 51 is in its normal position shown, the contact 53 engages the contact 54. A stop 55 on the support limits the counter clockwise movement of the arm 51 when it has been moved to open the contacts 5354. The switcharm 51 has also a finger 56, which normally lies adjacent to the end 29 of the stem 28.

The operation of my invention may be described as-follows: With the parts in the positionshown, which is the normal unenergized position, if current of a suitable value, to be described, flows in the winding 10, the magnetic flux in the gap 21 will lift the plunger 14 and cause the upper end 29 of the stem 28 to strike the finger 56 of the switcharm 51 and rotate theswitcharm in the counter clockwise direction, separating the contacts 5354, the arm coming to rest against the stop 55. The minimum overload current at which the plunger 14 will be lifted, and the stem 28 will open the contacts, as above described, is predetermined by thelength of the adjustable airgap 20. When this value of current flows in the winding, the flux in the gap 21 is sufiicient to lift the plunger 14 against its weight and that. of the stem 28 and tail piece 30, and the piston 32 attached thereto. The upward movement of the plunger 14 is retarded by the piston 32 in the usual manner, the rate preventin valve. hen the piston in moving u 'wardly passes the enlargement at 45, t e

fiow of fluid around it is thereby suificiently increased to enable the piston to move practically freely. This gives a quick movement to the latter part of the travel of the stem I piston to that above it.

If the overload in the winding 10 be above a second predetermined value, the pull on the plungerand piston, and hence on the cylinder 37, will be so great as to compress the spring 44, whereupon the cylinder will be lifted along with the plunger and piston, and the stem 28 will strike the finger 56 and open the contacts 53, 54, with practically no time-interval. The predetermined value at which this instantaneous operation occurs is adjustable by adjusting the tension of the spring 44, as hereinbefore described.

The length of the time interval above mentioned will be inversely proportional to the degree of the current overload between the minimum and maximum ,values for any one adjustment. The length of the time interval for any given overload current value may be adjusted by adjusting the vertical position of the cylinder 37 with respect to the piston 32, as already described, which correspondingly adjusts the distance between the piston in it's normal position and the shoulder 45. It' will be apparent that the adjustment of thetime interval for any given current and the adjustment of the instantaneously operating overloadcurrent value are iindependent of each other, aid

that the adjustment'of one does not'aifect,

7 gap 21 where the flux divides, a small portion being diverted into the wall 22 of the thimble, but, because of the restricted section of the thimble wall, the greater part passing across the air gap 21. The flux in the gap 21exerts on the plunger a magnetic pull of a certain amount. As the 139 plun er moves upwardly, the section of the thim 1e wall lying opposite to the upper end of the plunger becomes greater and greater, so that a greater and greater proportion of flux is diverted into the thimble wall 22, and a smaller and smaller proportion passes across the air gap 21. However, since the upward movement of the plunger decreases the reluctance of the magnetic circuit as a whole, and the total amount of flux accordingly increases, the amount-of flux passingacross the air gap and causing mag netic pull on the plunger remains practically cons. ant, with the-result thatat all positions of the plunger in its upward movement the magnetic pull thereon remains substantially constant. The absolute value of this constant pull is ro ortional to the degree of the overloa t e minimum value being a pull barely able to raise the moving.

parts. If now, after the occurrence of the overload, and during the upward movement of the plunger, the current falls below the minimum overload value, the pull on the plunger, no matter where it may be in its upward movement, will become insuflicient to hold it up and it will not continue its movement and open the contacts 5354, but will return to its normal position. If the overload current be very large, or if it be at or above the value at which instantaneous operation occurs, the ma netic flux in the thimble wall will be su cientsto substan tially saturate it, and therefore during the upward movement of the plunger the thimble wall will be unable to divert from the air gap 21 a greater and greater amount of flux, and therefore the pull in the gap 21 will increase so that the characteristic of the overload device to reset without operating should the current fall after the plunger has begun its upward movement will disappear and the plunggr will inevitably comp ete its upward stro For the sake of simplicity I have not shown or described the circuit connections of the Winding 10 of the contacts 5354, but as is well understood in the art, the contacts 53 and 541 may be employed to control a main line switch which in turn controls the current in the winding 10, so that when the device operates to open the contacts 5354, the winding 10 thereupon becomes denergized and the movable parts of the device return to their normal position.

My invention is not limited to the exact forms of the parts shown in the drawing, since many changes may be made therein without departing from the spirit of my invention or sacrificing its advantages.

I claim- 1. In an electromagnetic device, a mag netic circuit, an energizing winding therefor, a cylindrical core member in the circuit, there being a cylindrical working airgap for the core member, and a magnetic member surrounding the gap and tapered externally in the directionopposite that which the movable member takes while closing the gap.

2. In an electromagnetic device, a winding, and a magnetic circuit energized thereby, the said circuit including a member external to the Winding, a core member fixedly secured to the external member and having a cylindrical opening therein closed at one end, and a cylindrical movable core member in the opening, there being a working air-gap between the movable core member and the closed end of the fixed core member, the latter being tapered externally around the air-gap in the direction op 0- site that which the movablecore mem er takes while closing the air-gap.

Signed at Cleveland, Ohio, this 30th day of June, 1917.

CHARLES H. RIPPL. 

